Ink jetting devices are known in the art, and thus extensive description of such devices is not required herein. As described in U.S. Pat. No. 6,547,380, which is hereby incorporated by reference herein in its entirety, ink jet printing systems generally are of two types: continuous stream and drop-on-demand. In continuous stream ink jet systems, ink is emitted in a continuous stream under pressure through at least one orifice or nozzle. The stream is perturbed, causing it to break up into droplets at a fixed distance from the orifice. At the break-up point, the droplets are charged in accordance with digital data signals and passed through an electrostatic field that adjusts the trajectory of each droplet in order to direct it to a gutter for recirculation or a specific location on a recording medium. In drop-on-demand systems, a droplet is expelled from an orifice directly to a position on a recording medium in accordance with digital data signals. A droplet is not formed or expelled unless it is to be placed on the recording medium.
There are at least three types of drop-on-demand ink jet systems. One type of drop-on-demand system is a piezoelectric device that has as its major components an ink filled channel or passageway having a nozzle on one end and a piezoelectric transducer near the other end to produce pressure pulses. Another type of drop-on-demand system is known as acoustic ink printing wherein an acoustic beam exerts a radiation pressure against objects upon which it impinges. Still another type of drop-on-demand system is known as thermal ink jet, or bubble jet, and produces high velocity droplets.
In a typical design of a piezoelectric ink jet device utilizing phase change or solid inks printing directly on a substrate or on an intermediate transfer member, such as the one described in U.S. Pat. No. 5,372,852, which is hereby incorporated by reference herein in its entirety, the image is applied by jetting appropriately colored inks during four to eighteen rotations (incremental movements) of a substrate (an image receiving member or intermediate transfer member) with respect to the ink jetting head, i.e., there is a small translation of the print head with respect to the substrate in between each rotation. This approach simplifies the print head design, and the small movements ensure good droplet registration. At the jet operating temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the recording substrate, either directly or via an intermediate heated transfer belt or drum, they quickly solidify to form a predetermined pattern of solidified ink drops.
As noted, ink jet printing processes may employ inks that are solid at room temperature and liquid at elevated temperatures. Such inks may be referred to as hot melt inks or phase change inks. Advantages of a phase change ink in ink jet printing are elimination of potential spillage of the ink during handling, a wide range of print density and quality, minimal paper cockle or distortion, and enablement of indefinite periods of nonprinting without the danger of nozzle clogging, even without capping the nozzles.
Solid inks for piezoelectric ink jet printing have been designed to successfully print in a transfix mode wherein the ink is jetted onto an intermediate transfer drum. In the transfix printing process, the ink cools from the jetting temperature (broadly, from about 75° C. and to no higher than about 180° C., and typically from about 110° C. to about 140° C.) to the drum temperature (typically from about 50° C. to about 60° C.), and, subsequently, as a substantially solid phase, the ink is pressed into a paper substrate. Such a process provides a number of advantages including vivid images, economy of jet use, and substrate latitude among porous papers. However, such ink designs can present problems when applied to coated papers. In general, the ink and the print process can fail to provide sufficient image durability in response to paper handling stresses such as scratch, fold and rub stresses.
A need remains for amorphous materials to provide certain characteristics to the printed ink, such as tack and robustness. Current processes for preparing amorphous material require use of a large amount of solvent and long reaction times, sometimes in excess of 45 hours. Current solvent-less reaction process for making amorphous resins for use in robust solid ink applications sometimes take in excess of 20 hours to complete. Moreover, while the reaction itself may not require a solvent, or very little solvent, significant amounts of solvent typically are used in the isolation and purification of the resulting amorphous resin component. As a consequence, a need remains for an improved process for preparing phase change or solid ink components that is cost effective, environmentally friendly, and efficient.